Don't get black-flagged in the pits for excessive speed! Driver-controlled device assists in keeping a safe speed. Set light for an rpm just under the limit, green LEDs flash when limit is reached. Or set device just over the limit, triggering red LEDs. Mount right on dash in clear driver view. Requires switch to activate speed window and Tach Set-Up Module (item No. 75083) or tach signal to set RPM window.